The invention relates to a clamping device for firmly clamping a cylinder packing or covering on a printing machine cylinder, the clamping device including a clamping seat, a clamping jaw cooperating therewith, and an eccentric shaft.
Such a clamping device is described, for example, in the published Non-prosecuted Japanese Utility Model Specification No. 2-104235. The trailing-edge clamping device shown in FIG. 2 of the aforementioned published specification for clamping printing plates includes a winding rod extending in the direction of the cylinder axis and having a clamping plate articulatedly connected thereto, the winding rod bearing an eccentric shaft for operating the clamping plate. In this clamping device, a clamping seat or support is formed directly on the winding rod. Neither the eccentric shaft nor the clamping plate is mounted in a support that is adjustable with respect to the clamping seat.
A drawback with respect to the operating convenience of this clamping device of the Japanese utility model is the rather small width of the opening between the clamping plate and the clamping seat, the printing plate being insertable into the opening only with great difficulty so as to attain the clamping position thereof.
Furthermore, there is described in the published German Patent DE 195 15 843 C1, corresponding to U.S. Pat. No. 5,642,669 to Becker, a device for clamping a printing plate on a plate cylinder, which does not, however, belong to the general type of clamping device mentioned in the introduction hereto.
Although the width of the opening thereof is sufficiently large, this clamping device of the German patent document has a drawback from another point of view. In order to release the end of the plate, pneumatic cylinders are required, by which a clamping element is pivotable counter to the action of clamping springs. In the case of this heretofore known device, manual release by a tool is not possible for the operator, because the clamping force of the clamping springs that has to be overcome is too high.
It is accordingly an object of the invention to provide a clamping device for firmly clamping a cylinder packing on a printing machine cylinder, the clamping device being operatable manually, and having a large opening width.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a clamping device for firmly clamping a cylinder packing or covering on a printing machine cylinder, the clamping device including a clamping seat, a clamping jaw cooperating therewith, and an eccentric shaft, comprising a support wherein the eccentric shaft and the clamping jaw are jointly mounted, the support being adjustable alternatively into a first support position and into a second support position relative to the clamping seat.
In accordance with another feature of the invention, the support is mounted in the printing machine cylinder so as to be pivotable about a support joint.
In accordance with a further feature of the invention, the clamping jaw is mounted in the support so as to be pivotable about a jaw joint.
In accordance with an added feature of the invention, the clamping device includes a spring borne by the support.
In accordance with an additional feature of the invention, the clamping jaw is returnable by the spring from a clamping position into a released position.
In accordance with yet another feature of the invention, the eccentric shaft has a safeguard against rotation assigned thereto for blocking rotation of the eccentric shaft when the support is in the first support position, and for enabling rotation of the eccentric shaft when the support is in the second support position.
In accordance with yet a further feature of the invention, the eccentric shaft is formed with a circumferential flat which, when the support is in the first support position, is located opposite a stop face on the outside of the support and formlockingly locks the rotation of the eccentric shaft.
In accordance with yet an added feature of the invention, the eccentric shaft, on at least one shaft end thereof, has a tapered shaft extension, a side face of the shaft extension forming the flat.
In accordance with yet an additional feature of the invention, the clamping device includes a coulisse assigned to the eccentric shaft, the coulisse being disposed on the printing machine cylinder and having a groove with an inner face forming the stop face, the coulisse having a widening of the groove which, when the support is in the second support position, enables the rotation of the eccentric shaft.
In accordance with another aspect of the invention, there is provided a printing machine having at least one clamping device with at least one of the foregoing features.
Thus, the clamping device according to the invention for firmly clamping a cylinder packing on a printing machine cylinder, having a clamping seat and a clamping jaw cooperating with the latter, and having an eccentric shaft, is distinguished by the fact that the eccentric shaft and the clamping jaw are jointly mounted in a support which can be adjusted alternatively into a first support position and a second support position relative to the clamping seat.
With this clamping device, a two-stage clamping operation may be implemented. In a first stage, the clamping jaw can be adjusted by a manual adjustment of the support from a wide-open jaw position with good accessibility for the insertion of one edge of a cylinder packing into a less-open jaw position. In the less-open jaw position, the clamping jaw does not yet exert full clamping action on the cylinder packing. However, the latter is secured against slipping out of the clamping position thereof. In a second stage, the clamping jaw is adjustable by a manually performable rotation of the eccentric shaft from the less-open jaw position into a completely closed jaw position with full clamping effect. The clamping device permits distortion-free and in-register firm clamping even of cylinder packings without a bent-over edge, which provides a precondition for subsequent uniform tensioning of the cylinder packing in the circumferential direction of the printing machine cylinder.
The following embodiments constitute developments of the clamping device according to the invention which are particularly advantageous in construction terms and ensure high operating security.
One embodiment is distinguished by the fact that the support is mounted in the printing machine cylinder so that it can be pivoted about a support joint.
A further embodiment is distinguished by the fact that the clamping jaw is mounted in the support so that it can be pivoted about a jaw joint.
A further embodiment is distinguished by the fact that the support bears a spring.
A further embodiment is distinguished by the fact that the clamping jaw can be returned by the spring from a clamping position into a released position.
A further embodiment is distinguished by the fact that the eccentric shaft has a rotation safeguard assigned thereto, which blocks rotation of the eccentric shaft when the support is in the first support position, and which enables rotation of the eccentric shaft when the support is in the second support position.
A further embodiment is distinguished by the fact that the eccentric shaft has a circumferential flat which, when the support is in the first support position, is located opposite a stop face on the outside of the support.
A further embodiment is distinguished by the fact that, on at least one shaft end, the eccentric shaft has a tapered shaft extension, a side face of the shaft extension forming the flat.
A further embodiment is distinguished by the fact that the eccentric shaft has a coulisse assigned thereto that is disposed on the printing machine cylinder and has a groove with an inner face forming the stop face, the coulisse having a widening of the groove which, when the support is in the second support position, enables the rotation of the eccentric shaft.
The clamping device according to the invention is suitable for firmly clamping various types of cylinder packings, for example, foil or film-like cylinder packings or those formed as flexible plates, on printing machine cylinders of rotary printing machines. For example, with the clamping device, it is optionally possible for plates based on an aluminum carrier, plates formed of polyester material, as well as rubber blankets for varnishing or coating the whole area, to be clamped onto a coating cylinder.
The clamping device permits a reliable, frictional and/or formlocking firm clamping of the cylinder packings to be effected, without requiring the edges thereof to be bent over for this purpose. A good frictional connection can be achieved by a directly clamping contact surface on the clamping seat, and/or the clamping jaw being roughened. In addition or as an alternative to these measures, a good formlocking clamping action can be achieved by the contact surface of the clamping seat and/or the contact surface of the clamping jaw being provided with knob-like formlocking elements which press into the cylinder packing.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a clamping device for firmly clamping a cylinder packing on a printing machine cylinder, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, wherein: